#include <bits/stdc++.h>
#define rep(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++)
using namespace std;

typedef long long ll;

template <typename T, typename S> bool chmax(T &a, S b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}

int main() {
    int n;
    cin >> n;
    ll a[3][n];
    rep(i, 0, n) cin >> a[0][i];
    rep(i, 0, n) cin >> a[1][i];
    rep(i, 0, n) cin >> a[2][i];
    ll dp[n + 1][3][3];
    rep(i, 0, n + 1) rep(j, 0, 3) rep(k, 0, 3) dp[i][j][k] = -1e18;
    dp[0][0][0] = 0;
    rep(i, 0, n) {
        rep(j, 0, 3) rep(k, 0, 3) {
            rep(nj, 0, 3) {
                if (nj <= j) {
                    chmax(dp[i + 1][nj][k], dp[i][j][k] + a[nj][i]);
                } else {
                    int ad = nj - j;
                    if (k + ad < 3) {
                        chmax(dp[i + 1][nj][k + ad], dp[i][j][k] + a[nj][i]);
                    }
                }
            }
        }
    }
    auto debug = [&]() {
        rep(i, 0, n + 1) {
            rep(j, 0, 3) {
                rep(k, 0, 3) cout << dp[i][j][k] << " ";
                cout << endl;
            }
            cout << endl;
        }
    };
    // debug();
    ll ans = 0;
    rep(j, 0, 3) rep(k, 0, 3) chmax(ans, dp[n][j][k]);
    cout << ans << endl;
}